Three unbiased coins are tossed simultaneously. Find the probability of getting:
(i) at least one head.
(ii) exactly one tail.
(iii) two heads and one tail.

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Accepted Answer

Step 1: Total number of possible outcomes $= 2^3 = 8$: $\{HHH, HHT, HTH, THH, HTT, THT, TTH, TTT\}$
Step 2: (i) $P(	ext{at least one head}) = 1 - P(	ext{no head}) = 1 - \frac{1}{8} = \frac{7}{8}$
Step 3: (ii) $P(	ext{exactly one tail}) = \frac{3}{8}$
Step 4: (iii) $P(	ext{two heads and one tail}) = \frac{3}{8}$

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